Oil pollution is a serious environmental concern in shipping, the oil production industry and on industrial lands using heavy machinery or oil storage that contaminates groundwater. Many chemical and mechanical strategies have been utilized to remediate oil contamination, such as booms, skimmers, pumps, dispersants, absorbents and phytoremediation. Each of these techniques has limitations, such as cost or inability to remove all types of oil. For example, none of these techniques has been satisfactory in dealing with emulsified oil in water. Oil is often spilled into soil and ground water from ruptured storage tanks. The most commonly spilled oil is crude oil, which is sometimes spilled accidentally, for example, after a ship collision, but more commonly enters the environment when ships empty bilge tanks. The behaviour of oil in water depends on the type of oil as well as conditions such as water and air temperature, wave motion and wind. Spilled oil will typically spread out, the lighter, more volatile components of oil will evaporate and wave movements will mix water into the oil creating a heavy and sticky emulsion (typically a water in oil emulsion). This type of emulsion, called a mechanical emulsion, is difficult to remove from water.
There is also a particular need for compositions that separate chemical emulsions from water. These emulsions form in oily water when surfactants, such as detergents, are present along with the oil. For example, detergents used to clean ships often wind up in wastewater in bilge tanks along with crude oil. Detergents have an oleophilic hydrocarbon chain and a hydrophilic head. When detergent contacts oil, the oleophilic portion of the surfactant adheres to the oil and the hydrophilic portion remains attracted to water. Therefore, chemical process associated with creation of such emulsions result in the oil molecules becoming partially or wholly surrounded by surfactant molecules, preventing the oil molecules from contacting other oil droplets or coalescing surfaces to allow them to coalesce. For this reason, chemically emulsified oil is very difficult to remove from water.
Existing oil separation technologies which utilize passive treatment processes are ineffective at separating chemically emulsified oils, those formed by the interaction of oily water with surfactants. At present the only practical ways of removing such emulsions in industry involve active treatment measures such as addition of de-emulsifying chemicals to break the chemical emulsions. Another approach involves addition of chemicals to attach to the surface of the surfactant/oil particles so as to change their density relative to the carrier fluid, so they can be separated more easily by gravity. Membrane filtration systems are also used such as systems in which the pore spaces of the membrane are so small that it can filter out surfactant/oil molecules from the water. There are also various forms of coagulation/filtration processes which use chemicals to agglomerate the surfactant/oil molecules so they can be separated more easily by gravity separation. All of these processes involve significant capital, operational and maintenance costs, as well as handling and disposal issues for the chemicals being used. This has led industry to search for easier and more efficient passive solutions for separating chemically emulsified oils from water. There remains a need for simple, inexpensive absorbent which can capture any type of oil and other oleophilic compounds, including oils that are very difficult to separate from water, such as mechanically or chemically emulsified oil. As well, there is a need for a simple and effective oil separator which can be installed next to industrial equipment, such as on a ship so that that oil can be collected and properly disposed of so that it does not enter waste water, such as bilgewater.